Method of successively cutting and differentially hardening a toothed member



March 15, 1949 A. E. SHORTER METHOD OF SUCCESSIVELY CUTTING ANDDIFFERENTIALLY HARDENING A TOOTHED MEMBER Filed April 19, 1944 4Sheets-Shet 1 Rm m m0 H 5 E T R E B L A A TTORNEY March 15, 1949. A. E.SHORTER 2,464,351 METHOD OF SUCCESSIVELY CUTTING AND DIFFERENTIALLYHARDENING A TOOTHED MEMBER Filed April 19, 1944 4 Sheets-Sheet 2 IN VENTOR.

ALBERT E. SHORTER ATTORNEY March 15, 1949. SHORTER 2,464,351

METHOD OF SUCCESSIVELY CUTTING AND DIFFERENTIALLY HARDENING A TOOTHEDMEMBER Filed April 19, 1944 4 Sheets-Sheet 3 F/GG INVENTOR. ALBERT E.SHORTER A TTORNEY March 15, 1949.

A. E. SHCRTER METHOD OF SUCCESSIVELY CUTTING AND DIFFERENTIALLYHARDENING A T-OOTHED MEMBER Filed April 19, 1944 F/GZ 4 Sheets-Sheet 4INVENTOR. ALBERT E. SHORTER ATTORNEY Patented Mar. 15, 1949 M'ErrioiOFWSUTCCESSIVELY CUTTING AND DIFFERENTIALLY 'HARDENING A TOUTHED MEMBERAlbert Edwar Shorter, Sheflield, England; as-

sigrior to TheLinde Air Products Company, New York, N. Y., a corporationof Ohio Apji'ieatibii April 19, 1944, Serial No. 531.786

In Great Britain May 26, 1943 1 The present invention relates to theproduction of shaped ferrous metal parts having surface hardenedprofiles. v I It is common practice to produce shaped ferrous metalarticles, suchfa's templates, sprocket wheels, gear wheels and othermachine parts and tools Icy cutting the parts from metal blanks using ahigh temperature severing procedure. It is also l rnown that theprofiles of such shaped articles or selected portions thereof may besurface hardened by applying thereto high temperature heat to'raise thesurface to the critical point or above and then r'ais ei'y cooling orquenching the heated surface. The employment of two separate heatingoperations, the first in'the severing procedure, and the seconiclin'the' har dening process ,;is both time consuming and wasteful of heatenergy. H I v According to this invention a shaped ferrous metal parthaving a surface hardened profile is produced by subjecting ametalbl'ank to a high temperature severing procedure whereby the blankis progressively out to the required profile and progressively quenchingthe profiled surface before the temperature thereof has fallen below thecritical point, whereby a shaped metal part having a surface hardenedprofile is ohtained.

A preferred method of producing a shaped fermus metal part having a;surface hardened profile in accordance with this invention comprisesprogressively heating a man blank, directing an oxidising jet upon theheated surface to cut the desired profile and progressively applying astream of quenching fluid to the profiled surface before the temperaturethereof has fallen below the critical point. p I M The quench ispreferably applied in the form of an annular stream surroundingthe"cutting point thereby ensuring the quenching of the heated surfacedespite alterations, in the direction of relative prog'res'sionhet'weenlthe metal blank andthe heating and oxidising jet. I v

According to another feature: of'this'. invention apparatus forproducing a shaped ferrous metal part having a surface hardened profile,comprises in combination high temperature oxidising means forprogressivelyciitting tl' e' metal to the required profile and aquenching device adapted to apply a stream of quenching fiuidt'o theprofiled surface before the temperature thereof has fallen below thecritical point. M

In accordance with a further feature of this invention amachine forproducing a shaped ferrous metal part havi a'gsu-rface hardened profileeoinpi es" in combination a support uni- 4 Claims. (01. 1434)) versallymovable in a plane and bearing a tracer mechanism and a cutting burnerwithassociated' quenching device, the tracer mechanism com prising amechanically d'riven tracing roller in axial alignment with the cuttingburner normal to the plane of movement, and a template" er ranged toguide the tracing roller along a path conforming to the'desired'profil'e. The machine may be're'ndered substantially wholly automaticby providingin association with the template an electrical controlsystem including limitswitch'es adapted to be actuatedby the tracingroller as it traverse'e the template to turn on and on iht'he desiredsequence the supply of the fluids to the cutting burner and quenchingdevice.

The invention will now be described in further detail with reference 'tothe accompanying drawings in which:

Fig. 1 is a view in central longitudinal section of a compound cuttingburner and quenching device;

Fig. 2 is an underside 'view of the apparatus shown in Fig. 1; 1 Fig. 3is a View in central longitudinal section of a modified burner andquenching device;

Fig. 4 is 'a fragmentary plan view, somew at diagrammatic, illustratingthe path of traverse over the work of the apparatus shown in '2 and 3;

. Fig. 5 is 9; view inside elevation "of a machine for the production'ofa surface hardened picnic; a portion being broken away to expose a partof the mechanism; a u

I Fig. 6 is a plan view or the machine shown" in Fig. 5;

Fig. 7 is a plan view of "a detail or the machine shown in Fig. '6, 'onan nlarged scale, an

Fig. 8 is a View in side elevation of another de tail of the machine, onan enlarged scale. I

Referring to Figs. 1-, 2 and 3, a cutting burner B has a substantiallycylindrical fn'ozzle pro: vided in known mannerflwithfa central oiifi ce J delivering a jet of oxygen, the central ori'fi a ing: surrounded byan annular row of prehea g orfices Hl'deliveringfa combustible fuel suchas an oxyf'ace'tylene mixture. Around the wet dfth nozz'le'N there ismounted a hollow walled cylin drical quenching device Q, the inner waniii which is a sliding fit with the wall of are nb'zzie N. The quenchingdevice Q has an inlet in t P fitted with a conduit C for connection toasiipply o f 'qu"ejn'ching fluid which, in most instances; will be coldwater and 'a series of discharge orifices 10 for producing a'ring ofquenching jets arranged to impinge upon the heated surface along thecircumference of a circle centred on the cutting point. Since the innerwall of the quenching device Q is in close contact with the nozzle N,the quenching liquid delivered to the quenching device serves also ascoolant for the nozzle.

To prevent the quenching fluid discharged from orifices from interferingwith the heating and cutting jets, a shield S is provided between thesejets and the quenching jets. The shield S may be constituted as anextension of the inner wall of the quenching device Q, the exensionprojecting forwardly of the nozzle N to terminate close to the surfaceof the work W being cut when the nozzle N is positioned at the correctdistance from the surface. Gas escape slots G may be formed in the endsurface of the shield S to permit the products of combustion to escapereadily.

As the distance of the nozzle N from the surface will need to be variedwith different thicknesses and composition of metal or alloy being cut,it is of advantage to arrange for the shield S to be adjustable withrespect to the nozzle N, so that the shield may be maintained close tothe work for all settings of the nozzle N. Withthe arrangement shown inFig. 1, this is achieved by simply sliding the quenching device Q, ofwhich the shield S forms an integral part up or down the nozzle N. Inthe modification shown in Fig. 3, which in all other respects issubstantially identical with that shown in Figs. 1 and 2, the quenchingdevice Q and shield S integral therewith threadedly engage the nozzle N.The requisite adjustment of the nozzle N with respect to the surface tobe cut is effected by screwing the quenching device Q about the nozzleN. A looking nut L may be provided for securing the quenching device inthe desired position.

The operation of cutting and hardening a profile using the apparatusshown in Figs. 1, 2 and 3 will be clear by reference to Fig. 4, where Jrepresents the cutting jet, H the line of impingement of the preheatingjets, and Q the line of impingement of the quenching jets upon thesurface of the work W. At the starting point, the preheating jets arelighted up and, after heating for the appropriate period as determinedby the thickness of the material being cut, the oxidising jet is turnedon. At the same instant the quenching jets are turned on and theapparatus is traversed over the material either by hand or by a machine,the line of traverse being either marked upon the surface beforehand ora template provided for guiding the cutting jet along the required path.The cutting operation raises the temperature of the metal along the lineof cut above the critical point and the temperature will not have fallenbelow this point when, in the course of traverse, the cut profile comesunder the influence of the quenching jets which rapidly cool the heatedsurface below the critical point and thereby produce a hardened surface.In Fig. 4 there is illustrated the cutting and hardening of a toothedprofile T, where the direction of traverse is constantly changing. Inadvancing along the tooth flank T already cut, the burner movedleftwardly but after passing the apex to cut the tooth flank T theburner moves rightwardly. By surrounding the cutting jet with an annularquenching jet, the quenching of the heated cut profile is ensuredwhatever the direction of traverse may be at any instant.

A machine for producing a shaped ferrous metal part having asurface-hardened profile in accordance with the invention is shown inFigs. 5 to 8 to which reference will now be made.

.4 For purpose of illustration the set up and operation of the machinewill be described in connection with the cutting from an annular blankwith sequent hardening of a component having a number of identicalprofiles uniformly spaced around the periphery. An example of such acomponent is a sprocket wheel.

The machine comprises a massive four-sided base Ill having a transversepartition H on which is mounted a support l2 for the work W. Where,

as in the present example, a number of profiles are to be producedarranged around the circumference of a circle, the work support l2comprises a turntable; where the profiles are disposed linearly, amachine slide would replace the turntable. The partition II has a drainl3 leading to an outlet M for the quenching liquid. To one side of thebase l0 there is secured a pedestal l5 supporting a vertical column [Bwhich carries an upper arm 11 and a lower arm l8 extending over the worksup-port l2. The two arms ll, l8, are slidably mounted on the column I6and are arranged to be clamped firmly thereto by means of clamps I9, 20,respectively.

At its end remote from column Hi, the upper arm I! carries a template 2|of form-magnetic material for propelling the cutting burner B andquenching device Q along the desired path. With the template 2| there isassociated an electrical control system comprising four limit switchesto be described in detail later, the switches being connected to acontrol cabinet 22 by current leads extending through a sheath 23. l

The lower arm I8 is articulated so as to be uni-- versally movable in aplane and is known in the cutting machine art as a folding gate arm. Thearm l8 constitutes a support for a tracer mechanism M and a cuttingburner B with associated quenching device Q. The tracer mechanism Mcomprises a mechanically driven mag netic tracing roller 24 arranged tobear against the template 2 l, the roller 24 being in axial alignmentwith the burner B normal to the plane of movement. The roller 24 isadapted to be energised by a magnet coil which causes the roller 24 toadhere to the edge of the template and is caused to travel around thetemplate by means of a driving motor 25, which may be a variable speedelectric motor, to which the roller 24 is coupled through a gear box.The construction and operation of such tracer mechanism is well known inthe art and no detailed description thereof is deemed necessary. Theburner B, which is se-- cured to the arm l8 by a clamp 26, is furnishedwith a nozzle N on which the quenching device Q is mounted as describedabove with reference to Figs. 1 and 2 or Fig. 3.

The cutting oxygen is supplied to the burner B through asolenoid-operated valve 21 and flexible conduit 28, the gaseous fuel forpreheating is supplied through a solenoid-operated valve 29 and flexibleconduit 30; the quenching liquid is supplied to the quenching device Qthrough a solenoid-operated valve 3! and flexible conduit 32. A pilotlight 33 supplied with a gaseous fuel through a flexible conduit 34 maybe provided to ignite the preheating jets.

In the particular example taken to illustrate this invention, namely theproduction of a sprocket wheel, the guiding surface or edge 35 to whichthe roller 24 adheres is an internal boundary formed by an opening inthe template 2| as will be clear from Fig. '7. The guiding edge 35 ismounted in vertical alignmentwith the work W and having been properlyorientated radially and circum'ferentially with respect thereto, theburnere with the quenchingdevice Q operates simultaneously through thesame pathas the roller 24 to produce a surface hardened profile in themanneidescribed above with reference to Figs. 1 to i. In sprocket wheelsand other toothed members, which in use are subject to wear and impactmainly along the flanks and root of each tooth, it is usually desirablefor the apex to have a less hard but tougher structurethan the flanksand root. The ensuing description shows howsuch differentially hardenedteeth may beautomatically produced insuccession around the periphery ofthe Wo k W- The sequence of operations involved in the production ofsuch a toothed member, starting at the apex of one tooth, moving along aflank and root and finally along the flank of an adjacent tooth to theapex thereof, isas follows:

a. The turning on of the preheating jets and subsequently of theoxidising jet with sequent starting of the burner along the desiredpath;

b. The turning on of the quenching jets as soon as the oxidising jet hasmoved a predetermined distance alonga tooth flank from the apex;

c. Theturning oil of the quenching jets as the burner approaches theapex of the second tooth;

d. The turning off of the preheating and oxidising jets when the apex ofthe second tooth is reached.

On completion of this sequence of operations, the burner is returned tothe starting position whilst the work is moved through one tooth spaceso that the apex of the second tooth becomes the starting point of thesecond sequence of operations. This is repeated round the wholecircumference of'the blank until the burner once again reaches the apexof the first tooth. I

Reverting to Fig. '7, the aforementioned operations a, b, c, d areinitiate'd'in turn at the four similarlyde'ttered points shown on theguiding edge of the template 2| by an'electrical control system now tobe described.

At each of the four points a, b, c, d there is a limit switch LSA, LSB,LSC, LSD respectively, the four switches being secured to template 2|and connected to relays (not shown) housed in control cabinet 22, whichcause the solenoid perated valves 21, 29, 3|, to be turned on and off inthe desired sequence. A main switch MS, which may be of the push buttontype, controls the starting of motor 25 and the energisation of themagnet coil associated with the tracing roller 24. Switch MS is mountedon a switch panel SP secured to the front of the base l0 (Figs. 5 and6). A second push button switch OS is mounted on panel SP for breakingthe circuit, together with three further switches QV, FV, and 0V. SwitchQV is arranged to complete the circuit through the solenoid of quenchvalve 3| independently of the control exercised by the limit switches onthe template to permit of testing the supply of quenching medium;switches FV and 0V perform analogous functions in the circuits throughthe solenoids of fuel gas valve 29 and oxygen valve 21 respectively.

Except that switch LSA is associated with a latch mechanism LM, the fourlimit switches are identical, being simple make-and-break contactswitches which are closed in turn by the tracing roller 24 as ittraverses the guiding edges 35. The latch mechanism LM serves thefunction of preventing the roller 24 from traversing the guidi l'as f 5.f r eciecr ti d in e va I n rt s h tt s rqi is ter hat may b 'imfi-lparted to the work before the cutting x en is turned on. As will beclear by reference to Fig. 8, the lat-ch mechanism LMcomprises a roller36 carried by a stem 3'! slidably mounted in a guide 38 constituting anextension to ,the switch lever 39 of limit switch LSA. Stem3'l issecured to a flexible cable 49 by means of which itcan be retracted tolift the roller '36 out of the path of the tracing roller 24. A helicalspring 4| is provided to restore the roller 36 to its original positionwhen the cable 40 is'released'. h N v The sequenceof operation is asfollows; Y I Prior to starting, the tracing roller 2415 moved mum; he gued efi tin-i sinthe. i in ty bf. h po t O l s r o t e. mai swi ch motor2. t rt ter t the raci gro l'er- 24 whilst simultaneously the magnetcell which magnetises roller 24 is energised. The roller 24 movesslightlyaround the guiding edge 35 in a clockwise direction to abut,against the latch roller 35 causing switch 39 to close, further traverseof the tracing roller 24 aro'und the guide ing edge 35 being preventedby the latch roller 36 although the tracing roller 24 continues torotate. Closure of switch 39 energises the solehold-operated fuel gasvalve 29 to turn on the preheating gas to burner 13 which isignited atthenoZiZle N by the pilot light 33. After apreheating period,solenoid-operated valve 21 is energised to turn on the supply of cuttingoxygen to the nozzle N which moves round the guiding edge 35 in aclockwise direction and thenormal cutting operation proceeds along thetooth flank until the tracing roller 24 reaches thepoint b' where itabuts against the leverof limit switch LSB to close this switch, therebycausing the energisation of the solenoid-operated quench valve 3| toturn on the supply of quenching medium to the quenching device Q.Tracing roller 24 con: tinues to roll round the edge 35 untilit reachesthe point 0 where it closes limit switch LSC to turn off the supply ofquenching medium as the cutting operation approaches the apex of thesecond tooth. Further movement of the tracing roller 24 brings it to theposition d where it closes limit switch LSD to shut off both thepreheating gas and the cutting oxygen supply. Tracing roller 24continues to move round the edge 35 to return to the starting pointwhilst the work W is rotated to bring the apex of the second toothimmediately below the point a, whereupon switch MS is again closed andthe cycle of operations is repeated.

I claim:

1. Method of successively cutting and diirerentially hardening a toothedmember to cause the apex of each tooth to have a less hard but tougherstructure than the flanks and root, which comprises directing apreheating jet and subsequently a cutting stream of oxygen against ablank at the apex of a tooth, relatively propelling said jet and cuttingstream with respect to a blank to form a kerf along the flank and rootof said tooth and the adjacent flank of the next tooth, directing aquenching jet against the kerf as soon as the oxidizing stream has movedrelatively to the blank a predetermined distance along the flank of thefirst tooth and causing said quenching jet to follow said cuttingstream, turning ofi the quenching jet as the cutting stream approachesthe apex of the second tooth, and completing the cut to the apex of thesecond tooth.

2. Method of successively cutting and difierentially hardening a toothedmember to cause the apex of each tooth to have a less hard but tougherstructure than the flanks and root, which comprises directing apreheating jet and subsequently a cutting stream of oxygen against ablank at the apex of a tooth, relatively propelling the blank and saidjet and cutting stream along the flank and root of said tooth and theadjacent flank of the next tooth, directing quenching fluid against saidblank in an annular stream concentric with the cutting stream as soon asthe cutting stream has moved relatively to said blank a predetermineddistance along the flank of the first tooth,

causing said quenching stream to move with said cutting streamrelatively to the blank While maintaining such concentric relation andthereby insuring quenching of the heated kerf despite change indirection of relativemovement of the cutting stream, and turning offsaid quenching stream as the cutting stream approaches the apex of thesecond tooth.

3. Apparatus for successively cutting and differentially hardening atoothed member to cause the apex of each tooth to have a less hard buttougher structure than the flanks and root, which comprises a burnernozzle for directing a preheating jet and subsequently a cutting streamof oxygen against a blank at the apex of a tooth, a support for saidburner nozzle universally movable in a plane and bearing a tracermechanism for propelling said burner along the flank and root of saidtooth and the adjacent flank of the next tooth, a quenching devicesurrounding said burner nozale and constructed and arranged to projectan annular stream surrounding said preheating jet and cutting oxygenstream, a limit switch actuated by said tracer mechanism for turning onsaid quenching device as soon as the cutting oxygen stream has left theapex and has moved a predetermined distance along the flank of the firsttooth, and another limit switch actuated by said tracer mechanism forturning 01f said quenching device as the cutting stream approaches theapex of the second tooth.

4. Method of successively cutting and differentially hardening a toothedmember to cause the apex of a tooth to have a less hard and tougherstructure than the flanks, which comprises directing' a cutting oxygenstream against a blank at the apex of a tooth, relatively propelling theblank and said cutting stream to form a kerf along the flank, directinga quenching jet against the kerf as soon as the cutting stream has movedrelatively to the blank a predetermined distance along the flank andcausing said quenching jet to follow said cutting stream, turning offthe quenching jet before the cutting stream reaches the apex of thesecond tooth, and completing the cut to the apex of the second tooth.

ALBERT EDWARD SHORTER.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,145,875 Andres July 13, 19151,396,993 Carter Nov. 15, 1921 1,585,893 Coberly May 25, 1926 1,799,614Coberly Apr. 7, 1931 1,869,836 Anderson Aug. 2, 1932 1,969,840 GoddardAug. 14, 1934 2,051,915 Sykes Aug. 25, 1936 2,065,627 Taylor Dec. 29,1936 2,170,876 Shorter Aug. 29, 1939 2,187,731 Davis Jan. 23, 19402,190,360 Howard Feb. 13, 1940 2,208,121 Davis July 16, 1940 2,227,476Williams et a1 Jan. '7, 1941 2,274,005 Shorter Feb. 24, 1942 2,286,591Van Triest June'16, 1942 2,296,612 Gridley Sept. 22, 1942 FOREIGNPATENTS Number Country Date 632,258 Germany July 4, 1936 527,725 GreatBritain Oct. 15, 1940

